The present invention relates to a power transmission and a compressor employing the power transmission. The compressor includes a displacement compressor and a turbocompressor. The displacement compressor includes a reciprocating compressor and a rotating compressor. The reciprocating compressor includes a swash-plate, a wobble-plate, a crank, and a Scotch yoke compressor.
A conventional power transmission is adapted to a clutchless compressor, as referred in Japanese Patent Application Publication Laid-open No. 2000-87850. The compressor includes a boss in a housing. The boss rotatably supports a pulley, using a bearing. The housing houses a shaft. The shaft is disposed coaxially with the boss, projecting outwardly from the boss. The shaft has an end fixed to a hub.
The hub has a cover member fixed thereto, using a rivet. The cover member has recesses at the peripheral edge. The recesses are arranged on the identical circle about the shaft at an angular interval. Each of the recesses has a cushioning rubber therein which are adhered thereto. Each end of the recesses has a hole which rotatably houses a ball, a part of which is projected from the hole.
The pulley has a face opposed to the cover member. The face has a first hole on the identical circle, in which the ball is rotatably housed. The identical circle has a second hole thereon, in which the ball, disengaged from the first hole, drops.
The outer periphery of the pulley has a belt applied thereto. The belt is connected to a crank shaft. When driving an engine, the pulley is rotated, and power is transmitted to the shaft through the cushioning rubber, the cover member and the hub.
It is supposed that the clutchless compressor produces an abnormality such as seizing therein, and load torque goes over a predetermined value. Respective cushioning rubbers are deformed to disengage from balls. Respective balls are pressed by the cover member and are disengaged from first holes, going into second holes. This cuts off transmission of power from the pulley to the shaft, thus idling the pulley.
The conventional art has a complicated structure, the large number of components and productive steps, and high productive cost. In the conventional art, wear or age deterioration on the cushioning rubber reduces the threshold value of load torque when transmission of torque toward the compressor is cut off.